1. Field
The present disclosure relates generally to aircraft and, in particular, to rotorcraft. Still more particularly, the present disclosure relates to displaying vertical situation awareness information for rotorcraft.
2. Background
A rotorcraft, also referred to as a rotary wing aircraft, is a type of aircraft that uses lift generated by revolving rotor blades to fly. These types of aircraft are used for performing many different operations. For example, different types of rotorcraft include, without limitation, police helicopters, logging helicopters, medical helicopters, firefighting helicopters, military helicopters, cargo-carrying helicopters, tilt-rotor aircraft, autogyros, rotary wing unmanned aerial vehicles, and/or other types of rotorcraft.
During flight, an undesired event may occur. The undesired event may be, for example, without limitation, a loss of an engine, a loss of multiple engines, a loss of tail rotor effectiveness, and/or some other suitable type of undesired event. In response to an undesired event occurring during flight, an operator of the rotorcraft may initiate maneuvers to make a safe landing on the ground. For example, autorotation may be used to safely land the rotorcraft.
However, in some cases, depending on the current combination of altitude and airspeed of the rotorcraft, autorotation of the rotorcraft to a safe landing may not be possible. Further, a number of parameters at a particular time during the flight, such as gross weight of the rotorcraft, density altitude of the rotorcraft, and/or other factors may affect the combinations of altitude and airspeed at which the rotorcraft is able to use autorotation to safely land on the ground without undesired effects to the rotorcraft and/or occupants of the rotorcraft.
Currently, operators of rotorcraft are required to learn how to use height-velocity diagrams to identify the combinations of altitude and airspeed to avoid during flight. These combinations of altitude and airspeed form regions that may be identified using, for example, height-velocity diagrams. Height-velocity diagrams are graphs presenting altitude above ground versus calibrated airspeed. The altitude above ground may be, for example, the altitude of the lowest point on a wheel of the rotorcraft above the ground.
Height-velocity diagrams may be used to identify the combinations of altitude and airspeed to avoid during flight. By avoiding these combinations of altitude and airspeed, the rotorcraft can use autorotation to descend to a safe landing in response to an undesired event occurring during the flight.
These height-velocity diagrams are graphs that are illustrated on physical pieces of paper in books, manuals, and/or binders. Looking up the correct height-velocity diagram for a particular type of rotorcraft, a particular set of parameters for a flight for the rotorcraft, and identifying the combinations of altitude and airspeed to be avoided during the flight may take more time and/or effort than desired.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as other possible issues.